This invention relates to a composition and method for the alleviation of disease symptoms and the treatment of abnormal conditions occurring in the pelvic region related to smooth muscle contractions involving male sexual dysfunction and urinary symptoms, inflammation and treatment of several common diseases of the prostate including prostatitis, benign prostatic hyperplasia and adenocarcinoma of the prostate. The symptoms covered by this invention are all related to medical problems associated with the genitourinary tract. About half of the male population experience symptoms of prostatic inflammation during adult life. Benign prostatic hyperplasia (BPH) is a disease which is related to aging and associated changes in circulating hormones. As the hyperplastic prostate enlarges, it compresses the urethra and may cause incomplete emptying of the bladder. The most common treatment for BPH is surgery. Balloon dilation or drug therapy using .alpha.1 blockers such as terazosin and prazosin is used in some cases. Antiandrogen therapy may also relieve prostatic obstruction.
Carcinoma of the prostate is a significant cause of death in men over 55 years of age. The etiology of prostatic carcinoma is unknown. Early carcinoma of the prostate is asymptomatic. As the disease spreads, it may cause urinary obstruction. Determination of serum acid phosphatase is a basic screening test for metastatic prostate cancer. Elevation of serum prostate-specific antigen (PSA) level in the serum is the most sensitive test for early detection of prostatic cancer. The serum PSA level may be elevated with localized disease, while elevation of acid phosphatase level usually indicates extra-prostatic disease. Following diagnosis and treatment, serial determinations of serum PSA levels are done for assessing response. Treatment includes surgery, radiation and hormonal therapy. Cytotoxic chemotherapy has so far not proven effective.
Protease inhibitors are classes of compounds commonly found in many different types of foods, such as legumes, cereals, nuts, fruits and vegetables. One of the best characterized protease inhibitors is the Bowman-Birk Inhibitor (BBI) which is derived from soybeans. It is a 71 amino acid chain with 7 disulfide bonds that binds 1:1 with trypsin and chymotrypsin at different binding sites and has a molecular weight of approximately 8000.
In vivo and in vitro studies of protease inhibitors, and BBI in particular, have shown them to be effective anticarcinogenic agents. It has been shown that the enzyme-inhibitor described by Bowman, Proc. Soc. Exptl. Med. 1946, 63, 547 and Birk et al., Bull. Res. Council Israel 1962, Sec. 1, 11, 48 and Biochim. Biophys. Acta 1963, 67, 326, and subsequently referred to as the Bowman-Birk Inhibitor (BBI), possesses certain physiological activity that prevents, or at least greatly reduces, radiologically or chemically induced malignant transformation of cells in culture and in experimental animals.
Yavelow et al., Proc. Natl. Acad. Sci. USA 1985, 82, 5395-5399, reported that a crude soybean extract, if defatted with acetone, effectively blocked cell transformation in vitro. These observations, with epidemiological data, suggested BBI as a putative dietary anticarcinogen, particularly with respect to colon cancer.
Weed et al., Carcinogenesis 1985, 6, 1239-1241, disclose that an extract of soybeans containing the Bowman-Birk protease inhibitor added to the diet of dimethylhydrazine (DMH)-treated mice resulted in a significant suppression of adenomatous tumors of the colonic mucosa. DMH-induced colon cancer in mice is generally regarded as an excellent animal model for the human disease, with carcinogen treatment inducing adenocarcinomas of the colon and rectum which are similar to the tumors arising in the human colon suggesting the possibility that a dietary additive of the sort studied might confer some protection against the development of human colon cancer without undesirable side effects. The BBI extract and methods for its preparation were as described by Yavelow et al., Cancer Res. 1983, 43, 2454-2459; Proc. Natl. Acad. Sci. USA 1985, 82, 5395-5399.
Messadi et al., JNCI 1986, 76, 447-452 demonstrated that a soybean extract containing the protease inhibitor BBI suppresses 7,12-dimethyl-benza!anthracene (DMBA)-induced carcinogenesis in the hamster cheek pouch. This oral cancer model has the same histopathology, growth pattern and precancerous lesions as the most common form of human oral cancer, squamous cell carcinoma. It was shown in this study that hamster cheek pouch carcinogenesis can be inhibited by BBI and suggested that human oral carcinogenesis might respond to BBI in a comparable manner. The BBI preparation used in this study was a crude extract of the inhibitor prepared as described by Yavelow et al., Proc. Natl. Acad. Sci. USA 1985, 82, 5395-5399.
Baturay et al., Cell Biology and Toxicology 1986, 2, 21-32 disclose that a BBI preparation, wherein a crude soybean extract is defatted with acetone, suppresses radiation and chemically induced transformation in vitro, with or without enhancement by the co-carcinogen, pyrene. Yavelow et al., 1985, show that either pure BBI or the BBI extract prepared in accordance with their methods suppresses radiation induced transformation in C3H10T1/2 cells. Kennedy et al., 1984, report that either pure BBI or the BBI extract prepared in accordance with their method reduce the levels of chromosome abnormalities in cells of patients with Bloom's syndrome (a genetic disease in which the high levels of chromosome abnormalities are thought to predispose the patients to a higher than normal cancer incidence) . Still, other studies suggest that soybean-derived protease inhibitors can have suppressive effects on skin, breast and liver carcinogenesis in vivo.
Kennedy et al. in Anticarcinogenesis and Radiation Protection, edited by Cerutti et al., Plenum Pub. Co. 1987, pp. 285-295, disclose that BBI suppresses carcinogenesis in various systems using a crude BBI extract prepared by defatting soybeans with acetone. Their results suggested that very low concentrations of BBI-type protease inhibitor preparations would be effective as chemopreventive agents for colon cancer. There was no evidence to suggest that the use of protease inhibitors as chemopreventive agents would be complicated by possible toxicity problems.
St. Clair et al., Cancer Res. 1990, 50, 580-586, report that the addition of 0.5% or 0.1% semi-purified BBI to the diet of DMH-treated mice resulted in a statistically significant suppression of angiosarcomas and nodular hyperplasia of the liver and colon carcinogenesis. The results of this study also indicate that BBI, included as 0.5% of the diet or less, had no adverse effect upon the health of the mice but had the capacity to suppress liver and colon carcinogenesis.
A soybean extract enriched in BBI, termed Bowman-Birk inhibitor concentrate (BBIC) , has achieved Investigational New Drug Status from the Food and Drug Administration and human trials to evaluate it as a human cancer chemotherapeutic agent have begun.
Frenkel et al. Carcinogenesis 1987, 8(9), 1207-1212 monitored formation of H.sub.2 O.sub.2 by 12-O-tetradenoyl-phorbol-13-acetate (TPA)-activated polymorphonuclear leukocytes (PMNs) in the absence or presence of protease inhibitors and/or superoxide dismutase (SOD) . Protease inhibitors tested include potato inhibitors 1 (PtI-1) and 2 (PtI-2) , a chymotrypsin inhibitory fragment of PtI-2 (PCI-2) , chicken ovoinhibitor (COI), turkey ovomucoid ovoinhibitor (TOOI), Bowman-Birk inhibitor (BBI), lima bean inhibitor (LBI) and soybean (Kunitz) trypsin inhibitor (SPTI). The order of activity, as measured by inhibition of H.sub.2 O.sub.2 formation, was PtI-1.gtoreq.PCI-2&gt;PtI-2&gt;COI&gt;BBI.gtoreq.TOOI&gt;LBI&gt;SBTI thus showing that protease inhibitors specific for chymotrypsin, but not those that are trypsin-specific, are capable of inhibiting formation of active oxygen species during the oxidative burst of stimulated human PMNs. BBI was characterized as an inhibitor of both chymotrypsin and trypsin.
Perlmann et al., Methods in Enzymology 1970, 19, 860-861, have described an elaborate method for obtaining BBI from a defatted soybean extract.
U.S. Pat. No. 4,793,996 (Kennedy et al.) discloses a process comprising treating soybeans with acetone, followed by ethanol extraction and acetone precipitation for obtaining BBI. The soybeans may be defatted prior to acetone treatment. In addition, BBI may be further purified by conventional techniques. Kennedy et al. discovered that in the conventional process for preparing BBI from soybeans, a factor remained which adversely affected the ability of BBI to inhibit the malignant transformation of cells. If the factor was removed, the resulting BBI product was capable of inhibiting the malignant transformation of cells. It was found to be possible to remove this factor by treating the soybeans with acetone prior to the ethanol extraction step taught by Perlmann et al.
Kennedy et al. teach that it is unnecessary to carry out a procedure requiring complete purification of the extract to the point where the product contains only a single protein. Instead, they found it effective to stop the purification procedure at a point where a crude inhibitor extract is obtained. This crude extract is itself edible and can be used as an inhibitor of malignant transformation of cells, for example, by oral ingestion. Kennedy et al. disclose a process for preparing a crude soybean extract containing an inhibitor of malignant cell transformation which comprises defatting soybeans and extracting said inhibitor from said defatted soybeans.